The film, in which alien spaceships destroy Los Angeles, London and Moscow before American forces lead an heroic counter-attack, has already been seen by close to 20 million people.
Independence Day, it is said, has become America's "must-see" film this year, promising a bonanza for Rupert Murdoch's 20th Century Fox.
A carefully-fanned campaign of hype was helped by cover stories on UFO fever in both Time and Newsweek magazines.
Polls showed that 48 per cent of Americans do believe in aliens and 29 per cent think that they have already made contact with Earth.
Timed to play to the flag- waving hoopla of the July 4th national holiday, Independence Day features a Jewish technical wizard, a black combat pilot, and a handsome white Protestant President combining to save the world.
Its aliens emerge as the worst kind of foreigner - a nasty loutish lot of intergalactic football hooligans, armed with fancy weaponry but not in the end frightfully smart. The leading characters remain cheerily upbeat in the face of world destruction and the film's message may be that there is not much to be afraid of any more. If nothing else, the plot confirms that America still wishes to hold its surrogate royalty, the president, intact.
If Buckingham Palace was zapped by a spacecraft, would the United Kingdom rally to the banner of Prince Charles?